Whether the partisan gerrymandering now at work has morphed from an unsavory (if long-tolerated) practice into an insidious distortion of democracy is being reviewed by the United States Supreme Court. It is a matter that also underlies this installment of Retro Report, a series of video documentaries revisiting major news stories of old to explore how they continue to shape modern events.

The jumping-off point is a 1986 Supreme Court ruling that prohibited what has come to be called racial gerrymandering. As practiced in some states — notably, though not exclusively, in the South — it spread the population of African-Americans and other minorities across several districts in state and federal legislative races. As a result, those groups had numbers too small in a given district to elect any of their preferred candidates, typically people of their own race or ethnicity.

To remedy the situation as demanded by the court, those states created new political boundaries, concentrating solid percentages of Black voters into what are oxymoronically referred to as majority-minority districts. That worked out splendidly for freshly elected Black officials and their constituents. Or so it seemed.

Soon enough it dawned on people, both Republicans and Democrats, that instead of gaining political power, African-Americans and other minorities had lost a fair amount of it. By being packed into a few districts, they had their influence weakened in surrounding areas — and there were many more of those places. Since Black voters tend to cast ballots for Democrats, the effect in some states has been to dilute Democratic strength, over all, and to make the majority of legislative districts solidly white and reliably Republican. In most Southern states, white Democrats elected to office at the district level are almost as rare as magnolia trees blooming in December.

“It’s an irony: more African-American districts meant less Democrats were elected,” Carter Wrenn, a Republican political consultant in North Carolina, said to Retro Report.

The malformations in political mapmaking — Goofy, Elephant, Squid and the rest of the menagerie — can be blatant. In Pennsylvania, the total vote cast for that state’s 18 House seats has long been divided more or less equally between Republican and Democratic candidates. Yet district lines are drawn in such a way that Republican dominance of those seats is overwhelming, by margins that have been as great as 13 to 5. In North Carolina, Republicans have managed to snag 10 of the state’s 13 House seats, or 77 percent, with only about 54 percent of the total votes cast.

Similar outcomes exist in some state legislatures. The pattern is not lost on people like Angela Bryant, a Black woman who was a state senator in North Carolina until two months ago. The legislature may have become more diverse during her years in office, but that did not make it friendlier to priorities set by her and other African-Americans. “In the big sense,” Ms. Bryant said about packing minorities into a few districts, “it rendered us powerless.”

To Jeffrey Toobin, a lawyer and a writer for The New Yorker who has studied this issue, partisan gerrymandering at its most flagrant has contributed to the polarization that now defines American politics. “It makes the more liberal Democrats likely to win,” he told Retro Report. “It makes the more conservative Republicans more likely to win. And they are less likely to cooperate with each other. And that gets us to the politics we have now.”

When done deftly, political gerrymandering gives a party a lock on certain legislative districts and dooms the opposition to virtual irrelevance for years. At the national level, this is most evident in House elections. Since the so-called Republican Revolution of 1994, when the G.O.P. won a majority of House seats for the first time in 40 years, party control in that chamber has changed hands only twice; by contrast, the Senate has shifted half a dozen times in that same period. By some estimates, gerrymandering at the state level accounts for about half of the Republicans’ advantage in the House, a majority they would lose with a party shift for some two dozen seats.

Is anything to be done about the extreme partisanship in play? While the Supreme Court has declared gerrymandering along racial lines to be unconstitutional, it has never done so when partisan considerations alone are at issue (even though, in some states, it is evident that in practical terms “racial” and “partisan” can be synonymous). Were the justices to act now, they would effectively be saying that modern line-drawing methods had gone beyond the point of being tolerable.

The court is considering cases of gerrymandering in Wisconsin, by a Republican legislative majority, and in Maryland, by Democrats. It may also take into account mapmaking ruled invidiously partisan by lower-court judges in North Carolina and Pennsylvania, both in Republican hands. Critics of those gerrymanders argue that they violate the 14th Amendment’s guarantee of equal protection and perhaps also the 1st Amendment’s assurances of the right to political association.

It is not clear what the court might do — or even if it will decide anything at all, let alone in time to affect this year’s midterm elections. Some of the justices have echoed predecessors who said this form of political finagling is the business of legislatures, not of the courts. That’s certainly the view of Dallas Woodhouse, executive director of North Carolina’s Republican Party, who told Retro Report, “It is my opinion that Democrats want to use the courts to do what they can’t win at the ballot box.”

CLYDE HABERMAN, a regular contributor to Retro Report, has been a reporter, columnist and editorial writer for The New York Times, where he spent nearly 13 years based in Tokyo, Rome and Jerusalem. Subscribe to our newsletter here and follow us on Twitter @RetroReport.

This article first appeared in The New York Times.